In a computer power supply implemented according to the ATX specification, there exists an issue of data loss or even hard drive damage caused by inaccessibility to reserve power for a computer, once damage occurs during utilization of the computer power supply. Therefore, manufacturers have proposed a backup power supply implemented according to an ATX casing specification, and a patent related to the casing thereof can be referred from the disclosure of US 2017/0139451 A1. The casing uses a plurality of separation plates provided and a plurality of guide plates in a first body to define a space for installing two backup power supplies. However, during the installation process of the separation plates and the guide plates, these components need to be accurately aligned, and any slight deviation can disfavor the configuration of the two backup power supplies. In addition, the structure disclosed by the above patent is complicated.
From another perspective, the above backup power supply includes only two backup power supplies capable of performing plugging and plugging, and a power management bus circuit board of the backup power supply is provided in a fixed form in the casing, such that the power management bus cannot be easily replaced nor can it be upgraded according to user requirements.